Name and define the cell which was used for providing electric power in the Apollo space programme. Also write its one advantage.
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Solution and Explanation
Definition: It is an electrochemical cell in which the chemical energy of hydrogen and oxygen is directly converted into electrical energy.
Advantage: It is highly efficient and produces only water as the byproduct, making it environmentally friendly.
Top Questions on Electrochemistry
- Calculate the cell voltage of the voltaic cell which is set up by joining the following half-cells at 25°C:
Al/Al3+ (0.002 M) and Ni/Ni2+ (0.002 M)
Given: \( E^\circ_{\text{Ni}^{2+}/\text{Ni}} = -0.25 \, \text{V} \)
\( E^\circ_{\text{Al}^{3+}/\text{Al}} = -1.66 \, \text{V} \)
\( \log 5 = 0.6990 \)- CBSE CLASS XII - 2025
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- Calculate the cell voltage of the voltaic cell which is set up by joining the following half-cells at 25°C:
Al/Al3+ (0.001 M) and Ni/Ni2+ (0.001 M)
Given: \( E^\circ_{\text{Ni}^{2+}/\text{Ni}} = -0.25 \, \text{V}, \, E^\circ_{\text{Al}^{3+}/\text{Al}} = -1.66 \, \text{V} \)- CBSE CLASS XII - 2025
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Al/Al$^{3+}$(0.001 M) and Ni/Ni$^{2+}$(0.1 M)
Given: $E^\circ_{\text{Al}} = -1.66$ V, $E^\circ_{\text{Ni}} = -0.25$ V, $n_{\text{Al}} = 3$, $n_{\text{Ni}} = 2$- CBSE CLASS XII - 2025
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Reason (R): Chlorine has higher oxidation potential than H$_2$O.- CBSE CLASS XII - 2025
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Questions Asked in CBSE CLASS XII exam
On the given political outline map of India, locate and label the following with appropriate symbols:
- [(i)] Amravati – Stupa
- [(ii)] Banawali – Indus Valley Site
- [(iii)] (a) Ajmer – Territory under the control of the Mughals
- [OR] (b) Vijayanagara – Capital of Vijayanagara Empire
On the same outline map of India, two places have been marked as ‘A’ and ‘B’, as the centres of the Indian National Movement. Identify them and write their correct names on the lines drawn near them.
- CBSE CLASS XII - 2025
- Ancient Civilization
Read the given source carefully and answer the questions that follow:
Two rebels of 1857
Shah MalShah Mal lived in a large village in pargana Barout in Uttar Pradesh. He belonged to a clan of Jat cultivators whose kinship ties extended over chaurasee des (eighty-four villages). The lands in the region were irrigated and fertile, with rich dark loam soil. Many of the villagers were prosperous and saw the British land revenue system as oppressive: the revenue demand was high and its collection inflexible. Consequently cultivators were losing land to outsiders, to traders and moneylenders who were coming into the area.
Shah Mal mobilised the headmen and cultivators of chaurasee des, moving at night from village to village, urging people to rebel against the British. As in many other places, the revolt against the British turned into a general rebellion against all signs of oppression and injustice. Cultivators left their fields and plundered the houses of moneylenders and traders. Displaced proprietors took possession of the lands they had lost. Shah Mal’s men attacked government buildings, destroyed the bridge over the river, and dug up metalled roads – partly to prevent government forces from coming into the area, and partly because bridges and roads were seen as symbols of British rule. They sent supplies to the sepoys who had mutinied in Delhi and stopped all official communication between British headquarters and Meerut. Locally acknowledged as the Raja, Shah Mal took over the bungalow of an English officer, turned it into a “hall of justice”, settling disputes and dispensing judgments. He also set up an amazingly effective network of intelligence. For a period the people of the area felt that firangi raj was over, and their raj had come.
Shah Mal was killed in battle in July 1857.
How did the rebellion led by Shah Mal challenge the authority of the British?
- CBSE CLASS XII - 2025
- The Great Revolt of 1857
Read the given source carefully and answer the questions that follow:
Harappan Settlements
So far, more than 2000 Harappan archaeological sites have been discovered in the Indian sub-continent. Most of the sites are found located between the Indus and the Saraswati River basins. Nearly two-thirds of these settlements are in the Saraswati basin, suggesting its immense importance for the Harappan Civilisation. Among these, five major cities have been identified. These are Rakhigarhi, Mohenjodaro, Harappa, Dholavira and Ganweriwala. The remaining sites come under different categories such as Regional Centres, agricultural villages, ports and manufacturing centres.
Examine the significance of the concentration of Harappan settlements in the Saraswati Basin.
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Read the given source carefully and answer the questions that follow:
The bird leaves its nest
This is an excerpt from the Rihla:
My departure from Tangier, my birthplace, took place on Thursday... I set out alone, having neither fellow-traveller... nor caravan whose party I might join, but swayed by an overmastering impulse within me and a desire long-cherished in my bosom to visit these illustrious sanctuaries. So I braced my resolution to quit all my dear ones, female and male, and forsook my home as birds forsake their nests ... My age at that time was twenty-two years.
Analyse any one challenge that Ibn Battuta faced during his journey.- CBSE CLASS XII - 2025
- Travellers of Medieval India